1. Field of the Invention
The present invention relates to a method and an apparatus for manufacturing a synthetic resin hollow member by bringing a pair of synthetic resin molding half bodies into abutment each other and joining the resin-made half bodies together at their abutting portions, also relates to a method and an apparatus for manufacturing a synthetic resin hollow member with a filter (filtering material) or other intermediate element incorporated therein.
2. Description of Related Art
Conventionally, as a method for manufacturing a synthetic resin hollow member, as disclosed in, for example, Japanese Patent Application Laid-Open Publication (Kokai) No.7-217755, there is a known method utilizing the so-called xe2x80x9cdie slide injection (DSI) methodxe2x80x9d wherein a die assembly including a pair of dies is used such that one of the dies has a male molding portion and a female molding portion for molding one separate half body and the other die has a female molding portion and a male molding portion provided in opposed relation to the molding portions of the one die, and wherein after separate half bodies are simultaneously molded by using the die assembly (first injection), one of the dies is caused to slide relative to the other die so that separate half bodies left in the respective female molding portions are brought into abutment with each other before die clamping, with a molten resin being injected onto peripheral edges of the abutting portions (second injection) to join the two half bodies together.
According to this DSI method, productivity can be considerably enhanced over the conventional method in which molding of separate half bodies and abutting/joining of the half bodies are performed in completely separate processes. Also, the DSI method more reliably assures bond strength and a positive seal at the joint when compared with conventional methods of bonding the half bodies with adhesive or by heat fusion.
The DSI method can also be used to efficiently manufacture a synthetic resin hollow member with a filter (filtering material) or other intermediate element inside the finished product. In this case, after the synthetic resin hollow member is molded by the first injection as described in the above prior art, die opening is carried out once for insertion of a separately made intermediate element into one of the half bodies, after which the sliding and clamping of the dies are performed, the second injection is carried out.
In the DSI method, generally, a pair of male molding portion and female molding portion is provided in relative sliding direction on each die, and a single hollow member is obtained with every two die sliding operations. However, as a method for further improvement of the productivity in the DSI method, for example, in Japanese Patent Application Laid-Open Publication (Kokai) No.4-331117 or No.4-331123, there is disclosed the so-called xe2x80x9cdouble DSI methodxe2x80x9d wherein a set of male molding portion and female molding portions is provided in parallel (that is, plural rows are placed perpendicular to the die sliding direction) in each die.
According to this plural rows type (double) DSI method, one hollow member is obtained with each die sliding operation, and thus further improvement of productivity is achieved.
A problem with this conventional double DSI method is that the width of the die (that is, the dimension perpendicular to the die sliding direction) is unavoidably increased by disposing plural rows of molding portion pairs in each die, and more space is therefore required in this direction. Furthermore, this problem is even greater when the product being manufactured is long in this lateral direction.
Molding machine size is also related to the die width, and an increase in die width tends to increase production equipment cost and the cost of production. It is therefore necessary and desirable to keep the dies as small as possible so that the smallest possible molding machines can be used for production.
Also, when a synthetic resin hollow member with an intermediate element incorporated therein is manufactured using this DSI process, as described above, the intermediate element manufactured in a separate process is placed in one of the half bodies, after the first injection step and before the second injection step. This obviously means that a manufacturing process completely separate from that in which the hollow member half bodies are molded, mated, and bonded is required to manufacture the intermediate element incorporated into the hollow member. The separately manufactured intermediate elements must also be separately inventoried and managed, thus further complicating cost reduction efforts. Differences between half bodies molded in the first injection step and the intermediate element manufactured by the separate process, in molding conditions, temperature when the intermediate element is inserted into one of the half bodies, and other conditions also make it difficult to improve assembly characteristics and precision of the intermediate element assembled into the half bodies.
Another problem occurs when manufacturing two similar synthetic resin hollow bodies that have the same function and basic size and differ only partly in shape or orientation, such as right and left handed components. Conventional methods require dies that differ only in part, and the components are also manufactured in different production lots.
It will be obvious that die costs could be held down and production control significantly simplified if such nominally different products could be manufactured using the same dies as part of the same production lot.
It is therefore an object of the present invention to provide a method and an apparatus for manufacturing a synthetic resin hollow member whereby: an increase in die width is not incurred; one hollow member can be obtained with each die sliding operation; intermediate elements can be molded as part of the process for molding, mating, and bonding hollow member half bodies; or two different hollow bodies can be obtained using the same dies.
To achieve the above object, a method according to a first aspect of the present invention for manufacturing a synthetic resin hollow member bringing a pair of synthetic resin-made half bodies into abutment each other and joining these half bodies together at their abutting portions uses a molding apparatus for a die slide injection molding and comprises steps as described below. This molding apparatus more specifically comprises a first die having formed lengthwise thereto a series of molding portions in male-female-female-male sequence with a specific spacing therebetween, and a second die having formed lengthwise thereto a series of molding portions in female-male-female sequence with a specific spacing therebetween. The dies can be mutually opened/closed, and can be slid lengthwise a specific pitch relative to each other.
The steps of this manufacturing method include a die clamping step for closing and clamping the first and second dies. An injection step following the die clamping step forms first and second molding half bodies for a present cycle in a combination of male and female molding portions by injecting molten resin to a cavity formed between the dies, and joins first and second molding half bodies from a preceding cycle in a combination of female molding portions by injecting molten resin to their abutting portions. A removal step following the injection step opens the first and second dies and removes a hollow member formed by bonding half bodies from the previous cycle. A die sliding step following the injection step slides the first and second dies lengthwise a specific distance relative. to each other in a direction opposite that in which the dies were slid in the previous cycle. These steps are then repeated to manufacture one hollow member of bonded first and second half bodies each time the dies are slid relative to each other.
A molding apparatus used in this method for manufacturing a synthetic resin hollow member by bringing a pair of synthetic resin-made half bodies into abutment each other and joining the matched half bodies at their abutting portions, comprises a first die having formed lengthwise thereto a series of molding portions in male-female-female-male sequence with a specific spacing therebetween, and a second die having formed lengthwise thereto a series of molding portions in female-male-female sequence with a specific spacing therebetween. A die opening means opens and closes the first and second dies to each other, and a sliding means slides the first and second dies lengthwise a specific distance relative to each other. An injection means injects molten resin to a plurality of molding cavities formed between the closed first and second dies. Thus comprised, first and second half bodies for the present cycle are injection molded in a combination of male and female molding portions, and a hollow member is formed in a combination of female molding portions by bonding first and second molding half bodies from a preceding cycle by injecting molten resin to their abutting portions. As a result, a hollow member is yielded at each relative sliding operation of the first and second dies.
A manufacturing method according to another version of the invention is for manufacturing a synthetic resin hollow member having an intermediate element assembled therein by bringing a pair of synthetic resinmade half bodies into abutment each other after disposing the intermediate element therebetween, and then joining the matched half bodies at their abutting portions therebetween using a die slide injection molding apparatus. This molding apparatus comprises a first hollow member die having formed lengthwise thereto a series of molding portions in male-female-female-male sequence with a specific spacing therebetween; a first intermediate element die having an intermediate element molding portion and disposed at an end of the first hollow member die; a second hollow member die having formed lengthwise thereto a series of molding portions in female-male-female sequence with a specific spacing therebetween; and a second intermediate element die having an intermediate element molding portion and disposed at an end of the second hollow member die. The first and second hollow member dies can be mutually opened/closed and slid lengthwise a specific distance relative to each other. The first and second intermediate element dies are openable and closable to each other but are not slideable.
This manufacturing method comprises a die clamping step for closing and clamping the first and second hollow member dies and first and second intermediate element dies, respectively. An injection step following the die clamping step injects molten resin to a cavity formed between the hollow member dies and intermediate element dies respectively, thereby forming first and second molding half bodies for a present cycle in a combination of male and female molding portions, and an intermediate element for the present cycle in a cavity formed between the intermediate element dies, and bonding first and second molding half bodies from a preceding cycle in a combination of female molding portions by injecting molten resin to their abutting portions.
A removal step follows the first injection step to open the hollow member dies and remove the hollow member formed by the bonded hollow member half bodies from the previous cycle after first assembling therebetween an intermediate element from the previous cycle. An intermediate element assembly process then follows to place an intermediate element molded for the present cycle to either the first or second hollow member half for the present cycle. Next, a die sliding step slides the first and second hollow member dies lengthwise a specific distance relative to each other in a direction opposite that in which the dies were slid in the previous cycle. These steps are then repeated to manufacture one hollow member by bonding first and second half bodies with an intermediate element assembled therebetween each time the dies are slid relative to each other.
A molding apparatus for manufacturing a synthetic resin hollow member having a separate intermediate element incorporated therein by bringing a pair of synthetic resin-made half bodies after inserting the intermediate element therebetween, and then bonding the matched half bodies at their abutting portions therebetween, comprises a first hollow member die having formed lengthwise thereto a series of molding portions in male-female-female-male sequence with a specific spacing therebetween, a first intermediate element die having an intermediate element molding portion and disposed at an end of the first hollow member die, a second hollow member die having formed lengthwise thereto a series of molding portions in female-male-female sequence with a specific spacing therebetween, and a second intermediate element die having an intermediate element molding portion and disposed at an end of the second hollow member die. A die opening and closing means opens and closes, respectively, the first and second hollow member dies and first and second intermediate element dies to each other, and a sliding means slides the hollow member dies lengthwise a specific distance relative to each other while holding the intermediate element dies without sliding. An injection means injects molten resin to a plurality of molding cavities formed between the closed dies.
Thus comprised, with each relative sliding operation of the dies: first and second molding half bodies are injection molded in a combination of male and female molding portions for the present cycle; an intermediate element is injection molded for the present cycle in the intermediate element dies; and a hollow member is formed in registered female molding portions by bonding first and second molding half bodies formed in the preceding cycle and combined for the present cycle by injecting molten resin to abutting portions of the combined first and second molding half bodies. As a result, an intermediate element is assembled between first and second half bodies, which are then are bonded to yield a hollow member, at each sliding operation of the hollow member dies.
A further manufacturing method according to the present invention manufactures two different synthetic resin hollow member moldings using a single die slide injection molding apparatus. The injection molding apparatus in this method uses a first die having formed lengthwise thereto a series of molding portions in male-female-female-male sequence with a specific spacing therebetween, and a second die having formed lengthwise thereto a series of molding portions in female-male-female sequence with a specific spacing therebetween. The dies can be mutually opened/closed and slid lengthwise a specific distance relative to each other.
The manufacturing method comprises a first die clamping step for closing and clamping the first and second dies. A first injection step following the first die clamping step molds third and fourth molding half bodies for the present cycle in a combination of male and female molding portions by injecting molten resin to a cavity formed between the dies, and bonds first and second molding half bodies formed in the preceding cycle and combined in registered female molding portions for the present cycle by injecting molten resin to abutting portions of the combined first and second molding half bodies. A first removal step following the first injection step opens the dies and removes a first hollow member formed by bonding the first and second half bodies from the previous cycle. A first die sliding step slides the dies lengthwise a specific distance relative to each other in a direction opposite that in which the dies were slid in the previous cycle. A second die clamping step closes and clamps the first and second dies after the first die sliding step. A second injection step following the second die clamping step molds first and second molding half bodies for the present cycle in a combination of male and female molding portions by injecting molten resin to a cavity formed between the dies, and bonds third and fourth molding half bodies formed in the preceding cycle and combined in registered female molding portions for the present cycle by injecting molten resin to abutting portions of the combined third and fourth molding half bodies. A second removal step following the second injection step opens the dies and removes a second hollow member formed by bonding the third and fourth half bodies from the present cycle. A second die sliding step slides the dies lengthwise a specific distance relative to each other in a direction opposite that in which the dies were slid in the previous cycle. These steps are then repeated to sequentially manufacture one hollow member of bonded first and second half bodies and one hollow member of bonded third and fourth half bodies every two times the dies are slid relative to each other.
A molding apparatus for this manufacturing method more specifically comprises a first die having formed lengthwise thereto a series of molding portions in male-female-female-male sequence with a specific spacing therebetween, and a second die having formed lengthwise thereto a series of molding portions in female-male-female sequence with a specific spacing therebetween where the center male molding portion can be used in combination with the two center female molding portions in the first die. A mold opening means opens and closes the first and second dies to each other, and a sliding means slides the first and second dies lengthwise a specific distance relative to each other. An injection means injects molten resin to a plurality of molding cavities formed between the closed first and second dies.
Thus comprised, a first injection molding step and a second injection molding step are performed at every two relative sliding operations of the first and second dies. The first injection molding step molds third and fourth molding half bodies for the present cycle in a combination of male and female molding portions by injecting molten resin to a cavity formed between the dies, and bonds first and second molding half bodies formed in the preceding cycle and combined in registered female molding portions for the present cycle by injecting molten resin to a bonding interface between the combined first and second molding half bodies. The second injection step molds first and second molding half bodies for the present cycle in a combination of male and female molding portions by injecting molten resin to a cavity formed between the dies, and bonds third and fourth molding half bodies formed in the present cycle and combined in registered female molding portions for the present cycle by injecting molten resin to a bonding interface between the combined third and fourth molding half bodies. As a result, every two relative sliding operations of the first and second dies yields a first hollow member of bonded first and second half bodies, and a second hollow member of bonded third and fourth half bodies.
Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.